The number of heterosexual cases of AIDS is increasing steadily, raising concern about the public health burden of extensive heterosexual spread of HIV-1 infection. Currently available data are insufficient to measure the extent of infections among heterosexuals. Studies of miliary recruits and patients attending sexually transmitted disease (STD) clinics indicate that in high risk locations such as the Baltimore-Washington metropolitan area, the HIV-1 seroprevalence rate may be as high as 3% among heterosexuals between 18 and 27 years of age. Sentinel surveillance on college campuses is another approach to monitoring seroprevalence in sexually active young adults. A preliminary seroprevalence study was conducted among 3377 student volunteers at the University of Maryland at College Park (UMCVP) in the fall of 1988. Although some characteristics of this self-referred sample differed from the overall campus population, a heterogeneous sample of students with a high frequency of risk behaviors was recruited. Despite the high frequency of risk factors such as multiple sexual partners and history of STD among student volunteers, the HIV-1 infection rate was only 0.6 per 1000 students with HIV-1 infections documented in homosexual individuals only. Serial seroprevalence studies in this general student population are necessary to determine whether heterosexual spread of HIV-1 will occur on college campuses. Focused studies of high risk groups, such as students attending clinics for STD and older students enrolled in graduate programs in conjunction with large periodic surveys of undergraduate student populations will identify infections among students at increased risk. We therefore propose the following studies: (1) to determine the seroprevalence of HIV-1 infection among attendees of the UMCP STD clinics in year 1 and 3; (2) to determine the sero-prevalence of HIV-1 infection among undergraduates and graduate students at UMCP in year 2 and again in year 4 to monitor the trend in seroprevalence rates; (3) to identify risk behaviors for HIV-1 infection among surveyed students at UMCP; and (4) to assess the effectiveness of ongoing HIV-1 educational programs by monitoring changes in high risk behavior in this select population.